Flow Interference And Structural Improvement Between Rim Seals Of 1.5-Stage Turbine

Turbine rim seal is one of the important components of gas turbine secondary air system,the sealing and ingestion characteristics and the interaction between the purge flow and the mainstream directly affect the life of the turbine disc and the performance of the turbine and the gas turbine.In addition,the flow interference between the rim seals caused by the purge flow flowing out of the upstream cavity and then invading the downstream cavity with the main flow is also one of the factors affecting the sealing and ingestion characteristics of rim seals.Therefore,research on flow interference and design optimization between rim seals of a1.5-stage turbine is of great significance in the refined design of high-performance turbines.First of all,this paper aimed at the influence of turbine blades and vanes on the sealing characteristics of upstream rim seal cavity respectively,studies were carried out in a platform rings environment,only blades environment,only vanes environment and a turbine stage environment,The results show that vanes have more negative effects on sealing effectiveness than blades;compared with only platform rings environment,the mean sealing efficiency at the bottom of the clearance was reduced by 0.05,0.12 and 0.33,respectively,for the positions with blades and vanes acting alone and together.Secondly,in order to clarify the influence of the interference between rim seals on the sealing and ingestion characteristics of the downstream rim seal cavity in the real operating environment of the engine,the sealing effectiveness of the no upstream rim seal cavity and the downstream rim seal cavity with typical axial,chute and radial rim seals were studied in this paper.The results show that the maximum sealing efficiency of static disk can be increased by about 11 % due to the interference between rim seals,but the positive effect of radial seal structure is the worst.In addition,compared with the upstream rim seal cavity,the mainstream is more likely to ingestion into the area near the static disk.Then,this paper studied the flow details of purge flow when the upstream rim seal are typical chute and radial structure,and the flow details in the endwall area where the downstream purge flow interacts with the mainstream in a 1.5-stage turbine considering the interference between rim seals.The results show that the purge flow increases the loss in the height range of rotor blades and second stator blades by about 60% and 80% respectively,and the aerodynamic efficiency of a 1.5-stage turbine decreases by about 1.11% at most.Finally,based on the downstream rim seal properties,according to the flow characteristics of the ingestion of axial seal,added baffle to narrow the gap and the structural improvement of sealed convex teeth,so as to improve the sealing performance of the downstream rim seal cavity.The results show that the optimized seal structure can well prevented the gas ingestion in rim seal clearance and completely sealed the disc cavity.In this paper,researches have been carried out on sealing characteristics of upstream and downstream rim seal cavities of a 1.5-stage turbine with flow interference between rim seals,and studies on the interaction between purge flow and mainstream,as well as research on structural improvement of sealing structure designed to improve sealing performance of rear blade seals,which can provide relevant ideas for the fine design of turbine rim seal structure for advanced gas turbine in the future.